Simulations of the titration of linear polyelectrolytes with explicit simple ions: Comparisons with screened Coulomb models and experiments

Monte Carlo simulations of linear, weak polyacids and explicit simple ions have been performed in a spherical cell model to study the shift in the app arent dissociation constant. The simulations are performed in a canonical e nsemble with the apparent dissociation constant calculated in a procedure b ased on Widom's particle-insertion method. The effects of model parameters are discussed, for example, the influence of various distances of closest a pproach, and the results are compared to experiments as well as simulations with effective pair-potentials between monomers, both the screened Coulomb potential and an extended version that takes into account a distance of cl osest approach between monomers and simple ions. Results of the latter pote ntial are also compared to the experimental data, which are from poly(acryl ic acid), poly-D,L-glutamic acid and carboxymethyl cellulose.